This answer is not correct. You have multiplied by the 2 M NaCl concentration term rather than divide by this term. This problem is based on the algebraic relationship... volume₁ x concentration₁ = volume₂ x concentration₂. Remember that when you solve this equation for one of the terms, you must do the same operation on both sides of the equal sign. In this case, we need to divide both terms by the 2 M NaCl concentration term so that the units of concentration (molarity) cancel.